code: def update_select_test_file_dropdown(n_clicks):
      options = []
      ctx = dash.callback_context
      prop_id = ctx.triggered_id
      if prop_id == "anomaly-select-test-file-parent":
          files = file_manager.uploaded_files()
          for filename in files:
              options.append({"label": filename, "value": filename})
      return options
  
file_path: merlion/merlion/dashboard/callbacks/anomaly.py
imports: import logging
  import os
  import traceback
  import dash
  from dash import Input, Output, State, callback, dcc
  from merlion.dashboard.utils.file_manager import FileManager
  from merlion.dashboard.models.anomaly import AnomalyModel
  from merlion.dashboard.pages.utils import create_param_table, create_metric_table, create_empty_figure
label_desc: Use image node_id 2 for calling a global function with example usage: update_select_test_file_dropdown(n_clicks) and returns: options